Analysis of purity of Clostridium difficile toxin A derived by affinity chromatography on immobilized bovine thyroglobulin

Clostridium difficile toxin A separated by bovine thyroglobulin affinity chromatography was analysed for its purity by fast protein liquid anion-exchange chromatography (FPLC). By testing each FPLC fraction for cytotoxicity the affinity- purified toxin A specimen was shown to contain small amounts of contaminating toxin B. Coldhaemagglutination activity was detected in FPLC fractions corresponding to toxin A but not in those corresponding to toxin B. Toxin A obtained from bovine thyroglobulin affinity chromatography should be further purified to remove traces of toxin B.